A simple device effective for matrix-assisted laser desorption/ionization (MALDI) sample preparation, based on the spraying of matrix/sample solution through a stainless steel sieve (sieve-based device, SBD), has been employed for the preparation of MALDI samples of peptides, polysaccharides and high molecular weight proteins. The instrumental parameters, mainly the sprayer voltage, solution and auxiliary gas flows, and distances between sprayer-sieve and sieve-MALDI sample holder have been optimized. The MALDI spectra obtained by laser irradiation of the microspots so obtained, exhibit resolution and sensitivity higher than those achieved by the commonly employed dried droplets (DD) method. Worth noting is the fact that, in contrast to what is observed in the DD method, identical spectra are obtained by irradiation of different areas of the MALDI sample, showing that by using the SBD the matrix/analyte ratio is constant over the entire surface.
Copyright 2009 John Wiley & Sons, Ltd.